Compressed natural gas (CNG) vehicles require specialized refueling delivery systems. One such system utilizes high pressure storage vessels which are delivered full to a dispensing or filling station on shuttle trucks. A hose from the storage vessel is connected to the tank on the vehicle to be refueled, allowing CNG to flow from the storage vessel to the tank. A high pressure device, such as a compressor, applies pressure to the vessels as the CNG fuel flows to the vehicles. The high pressure device is required to compensate for pressure drops in the vessels resulting from dispensing the CNG.
The amount of CNG dispensed from the vessels is typically measured by a flow meter. Various types of flow meters are used by the industry including sonic nozzles, coriolis tubes and turbine-type flow meters. Each of these flow meters is expensive and represents a significant portion of the cost of the dispensing system. An accurate, less expensive method for measuring the amount of CNG dispensed is needed.